How the Brain of a Blind Person Rewires Itself

Do blind peo­ple real­ly have a sharp­ened sense of hear­ing? What is the expla­na­tion? This arti­cle reports the work of Ger­man researchers who looked at blind peo­ple’s brains to try to answer these ques­tions. They found out that indeed, blind peo­ple can under­stand speech even if sped up beyond the max­i­mum rate that sight­ed peo­ple can under­stand. This seemed pos­si­ble because the brain areas devot­ed to vision in peo­ple with eye sight turned out to be respond­ing to speech in blind people.

10 syl­la­bles per sec­ond [is] the absolute lim­it of com­pre­hen­sion for sight­ed peo­ple. Blind peo­ple, how­ev­er, can com­pre­hend speech sped up to 25 syl­la­bles per second.

brain scan­ner revealed that in blind peo­ple the part of the cere­bral cor­tex that nor­mal­ly responds to vision was respond­ing to speech.…somehow an unsight­ed per­son­’s brain rewires itself to con­nect audi­to­ry regions of the brain to the visu­al cortex.

A per­fect exam­ple of neu­ro­plas­tic­i­ty! Do you think this hap­pens  1) only in peo­ple who are born blind, or  2) only in peo­ple who lose sight lat­er in life,  or 3)  in both cases?

The answer is 2). Indeed, to be rewired con­nec­tions need to pre­ex­ist. This is not the case in peo­ple who are born blind since their visu­al cor­tex has nev­er received any visu­al stim­u­la­tion. It is only in peo­ple who lose sight lat­er in life, that the visu­al con­nec­tions can be rerout­ed to process audi­to­ry information.

How does it work?

The fact is that most of our sens­es have some inter­act­ing cir­cuit­ry between them, which is called cross modal­i­ty. […] These con­nec­tions between visu­al and audi­to­ry regions of the brain become strength­ened after los­ing sight.

Also, some regions of cere­bral cor­tex that bor­der visu­al and audi­to­ry cor­tices […] expand ter­ri­to­ry in blind peo­ple to make use of the idle cir­cuit­ry in visu­al cortex.

Relat­ed post: Brain Plas­tic­i­ty: How learn­ing changes your brain

About SharpBrains

SHARPBRAINS is an independent think-tank and consulting firm providing services at the frontier of applied neuroscience, health, leadership and innovation.
SHARPBRAINS es un think-tank y consultoría independiente proporcionando servicios para la neurociencia aplicada, salud, liderazgo e innovación.

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